Pressure wave generator

ABSTRACT

First and second shock wave generating cells are separated by a first resonant cavity. Third and fourth shock wave generating cells are arranged transverse to the first and second cells at opposite sides of and in communication with the first cavity. The shock waves from the cells collide in the first cavity. A second resonant cavity, which is terminated by a reflective strip of material, communicates with the outlet of the second cell. A plurality of cubicle auxiliary resonant cavities are formed around the side of the second cavity to intersect the plane in which the strip lies. A fifth shock wave generating cell is arranged transverse to the second cell in communication with the second cavity. Preferably, the shock waves generated by all the cells and the dimensions of the cavities are multiply related.

United States Patent -i191 1 Hughes Aug. 21, 1973 PRESSURE WAVEGENERATOR 3,514,956 6/1970 Bray 60/270 X 3,568,703 3/1971 Warren eta1... 137/815 [75] Inventor gz Hughes Ronmg 3,595,022 7/1971 Radebold eta1 60/270 R I 3,379,204 4/1968 Kelley et'al 137/81.5 3,398,758 8/1968Unfried 137/815 31 ssignee: Energy Sciences, Inc., Costa Mesa, 3,456,6687 1969 WheelenJr. 137/815 Calif, 3,614,961 10/1971 Nekrasov et a1....137/81.5 3,665,949 5/1972 Rivard 137/8l.5 [22] Filed: Feb. 2, 1971Primary Examiner-Samuel Scott U Appl L995 Attorney-Christie, Parker &Hale Related US. Application Data [63] Continuation-impart of Ser. No.855,321, Sept. 4, 7 ABSTRACT 1969, abandoned, and a conunuation-m-partof Ser. No. 13,977, Feb. 25, 1970, abandoned. First and second shockwave generating cells are sepa- 3 I rated by a first resonant cavity.Third and fourth shock [52] US. Cl 1. 137/823, 137/827, 235/201 ME wavegenerating cells are arranged transverse to the [51] Int. C1,... FlScl/l4 first'and second cells at opposite sides of and in com- [58] Fieldof Search 239/4; 235/201 ME; munication with the first cavity. The shockwaves from 60/249, 247, 270 R; 137/815, 13 the cells collide in thefirst cavity. A second resonant cavity, which is terminated by areflective strip of mate- [56] References Cited I rial, communicateswith the. outlet of the second cell. UNITED STATES PATENTS A pluralityof cubicle auxiliary resonant cavities are 3,175,357 3/1965 Klein 60/249x fmmFd Slde 'tersect 2.805545 9/1957 wilmanw 60/247 the plane 1n whichthe strip lies. A fifth shock wave gen- 3,005,310 10,19 Red" t I I60/249 crating cell is arranged transverse to the second cell in ,3 012/1962 Riordan 137/815 communication with the second cavity.Preferably, the 3,371,869 3/1968 Hughes 239/4 X shock waves generated byall the cells and the dimen- 3,389,97l 6/1968 Alliger 239/4 sions of thecavities are multiply related. 3,393,964 7/1968 Donnelly 239/4 X3,503,408 3/1970 Metzger 17 Claims, 7 Drawing Figures Patented Aug. 21,1973 3,753,304

5 Sheets-Shoet ll.

'9 55 i H55 w 3 INVENTOR.

I Patented Aug. 21, 1973 5 Sheets-Sheet Patented Aug. 21, 1973 33,153,304

' 3 Sheets-Sheet 3 H5. 7

1 PRESSURE WAVE GENERATOR CROSS REFERENCE TO RELATED APPLICATIONS Thisis a continuation-in-part of copending applications, Ser. No. 855,321,filed Sept. 4, .1969 and Ser. No. 13,977, filed Feb. 25, l970,'both ofwhich are now abandoned.

BACKGROUND OF THE INVENTION This invention relates to the generation ofpressure waves and, more particularly, to a pressure wave generator thisis particularly well suited for the PCV system of an internal combustionengine.

In my Pat. No. 3,554,443, which issued Jan. l2, 1971, there is discloseda shock wave generating cell in which a converging-diverging supersonicnozzle is formed by a fluid boundary layer. A primary inlet opening inthe cell couples fluid from a source to the converging-diverging nozzlefor conversion to supersonic flow and auxiliary inlet openings designedto form the boundary layer couple the source to the cell. As thepressure of the source varies, the boundary layer changes to adjust thethroat area of the convergingwaves propagates along the longitudinalaxis. The second cell is coupled to the cavity at the side wall suchthat the vertex of its shock waves propagates along an axis transverseto and intersecting the longitudinal axis. The distance between thepoint of intersection and each wall of the cavity and the otherdimensions are also multiply related. Preferably, the mass flow rate ofthe fluid passing through the second cell is substantially less than thefirst cell and is balanced by a thrid cell coupled to the cavity at theside wall opposite the second cell. The transverse shock waves areintroduced into the resonant cavity between two spaced shock wavegenerating cells arranged in series, as described in the precedingparagraph.

According to another aspect of the invention, a resonant cavity forconverting shock waves into coherent sonic waves is arranged in serieswith and downstream of one or more converging-diverging supersonicnozzles. In a preferred embodiment, the cavity has first and secondspaced ends and a longitudinal, preferably cy- I lindrical side wallextending about an axis between the diverging nozzle so the wavelengthof the principal shock waves tends to remain constant. The dimensions Iof the cell are selected so the wavelengths of the secondary pressurepulsations produced by the auxiliary openings and the cavities formedwithin the cell andthe wavelength of the principal shock waves aremultiply related. Thus, substantially coherent shock wave energyemanates from the cell.

SUMMARY OF THE INVENTION The invention is concerned with techniques forenhancing the'coherent pressure wave energy produced byconverging-diverging supersonic nozzles, particulary the shock wavegenerating cell disclosed in US. Pat. No. 3,554,443.

According to one aspect of the invention, a plurality ofconverging-diverging supersonic nozzles are arranged in spaced apartseries relationship. The princi pal wavelength of the shock wavesproduced by the nozzles and the space between the nozzles are multiplyrelated. In a preferred embodiment, an annular resonant spacer isdisposed in a housing between first and second shock wave generatingcells. The fluid stream flows from an inlet of the housing through thefirst cell, the spacer, and the second cell to the outlet of thehousing.

According to another aspect of the invention, a plu-' rality ofconverging-diverging supersonic nozzles are arranged transverse to eachother so the shock waves they produce collide and interact. In apreferred embodiment, the energy from a first shock wave generating cellis coupled to a resonant cavity for transverse resonant interaction withthe energy from a second shock wave generating cell. The resonant cavityhas a pair of spaced ends, a longitudinal side wall extending betweenthe ends, a longitudinal axis extending between the ends, and an exitand a solid reflective wall at one of the ends. The principal wavelengthof the shock waves produced by the first and second cells, the length ofthe cavity, and the width of the cavity are all multiply related. Thefirst cell is coupled to the cavity at the other end wall such that thevertex of its shock ends. At the first end, there are introduced shockwaves having a vertex that propagates along the axis. The principalwavelength of the shock waves and the length of the cavity are multiplyrelated to promote resonant action in the cavity. An exit from thecavity is formed at the second end to permit the sonic wave energy toleave the cavityafter reflection from the second end.

Preferably, the exit from the second end comprises two identical chordalopenings a solid reflective strip, the width of which is multiplyrelated to the wavelength. To enhance the intensity of the coherentsonic wave energy, hexahedral, preferablycubical, auxiliary cavities areformed around the side wall to intersect the plane in which the secondstrip lies. The auxiliary cavities intercept the energy as it isreflected outwardly from the second end, thereby providing additionalresonant action.

A compact sonic wave generator capable of producing coherent sonic waveshaving a high intensity can be formed by incorporating into a commonhousing the structural features described in the two precedingparagraphs. Such a generator is particularly well suited for insertionin a PCV return line.

BRIEF DESCRIPTION OF THE DRAWINGS The features of several specificembodiments of the best mode contemplated of carrying out the inventionare illustrated in the drawings, in which:

FIG. 1 is a side veiw of a shock wave generator incorporating theprincipals of the invention;

FIG. 2 is a side view of a sonic wave generator incorporating theprincipals of the invention;

FIG. 3 is a sectional view of the sonic wave generator of FIG. 2;

FIG. 4 is an exploded view of a sonic wave generator that incorporatesthe'elements of FIGS. 1 and 2 into a common housing;

FIG. 5 is a side sectional view of the spacer of FIG. 1 showing thedimensions of the resonant cavity;

FIG. 6 is a side sectional view of the spacers of FIG. 2 showing thedimensions of the resonant cavity; and

FIG. 7 is a schematic diagram of a PCV system incorporating a pressurewave generator in accordance with the invention.

In FIG. 1, a housing comprises a cylindrical tube 11, a cylindricalouter jacket 12, and tubular fittings 13 and 14. Fittings .13 and 14 arefixed to tube 11 by swaging or other means. Jacket 12, which surroundstube 11, has a force fit therewith. A shock wave generating cell 15, anannular spacer 16, and a shock wave generating cell 17 are disposedwithin tube 11 along its cylindrical axis 18 in abutting relationshipbetween the ends of fittings 13 and 14, as shown in FIG. 1. Thus, cells15 and 17 and spacer 16 fit snugly inside housing 10 as a singlecylindrical unit without being able to move. The space enclosed byspacer 16 between cells 15 and 17 comprises a resonant cavity 27.Cylindrical counterbores 19 and 20 are formed at diametrically oppositesides of jacket 12. Cylindrical shock wave generating cells 20,respectively, by force fits. A circular hole 23 through tube 11 and acircular hole 24 through spacer 16 couple cell 21 to cavity 27. Acircular hole 25 through tube 11 and a circular hole 26 through spacer16 couple cell 22 to cavity 27. Counterbores 19 and 20, cells 21 and 22,and holes 23 through 26 are all centered about a transverse axis 28 thatis perpendicular to axis 18 and intersects axis 18 at a point 29 withincavity 27.

As described in more detail in U.S. Pat. No. 3,554,443 the disclosure ofwhich is incorporated herein by reference cells 15, 17, 21, and 22 eachcomprise a cylindrical nozzle open at its downstream end and bounded atits upstream end by an end wall. The end wall has a large center holethat serves as a primary inlet for the nozzle and a plurality ofsmaller, equally spaced peripheral holes disposed about the center hole.The cylindrical side wall of the nozzle has a plurality of oppositelydisposed pairs of holes lying in a common plane near the downstream endof the nozzle for throat plane stabilization. The smaller peripheralholes and the throat plane stabilization holes serve as the secondaryinlets for forming the converging-diverging boundary layer. Acylindrical cell cover surrounds the nozzle to form with the cylindricalside wall of the nozzle an annular cavity. The cell cover completelyenclosesthe nozzle except for an opening at its upstream end thatcommunicates with the holes of the nozzle. Forthe purpose of discussion,it is assumed that cells 15 and 17 each have the dimensions and holediameters specified in U.S. Pat. No. 3,554,443 and cells 21 and 22 eachhave the dimensions and hole diameters specified in U.S. Pat. No.3,554,443 except for the diameter of the opening at the upstream end ofthe cell cover, which is assumed to be 0.097 inches. In other words,openings 30 and 31 of cells 15 and 17 respectively are twice as big indiameter as opening 32 of cell 22 and the corresponding opening of cell21 (not shown). As used in this specification, the term boundary layerformed shock wave generating cell refers to the type of device disclosedin U.S. Pat. No. 3,554,443, and the term boundary layer formedsupersonic nozzle refers to a device based upon the principles taught inmy U.S. Pat. No. 3,531,048, which issued Sept. 29, 1970, and isreferenced in U.S. Pat. No. 3,554,443.

It is further assumed that fitting 13 is connected to an atmospheric airsource at a temperature of 528 R and at atmospheric pressure, theopenings at the upstream 21 and 22 are maintained in counterbores l9 andend of the cell covers of cells 21 and 22 are exposed to atmosphericair, and fitting 14 is connected to an air receiver at a lower thanatmospheric pressure. The pressure difference across cells 15, 17, 21,and 22 induces a subsonic flow of air into the cells where'the air isconverted to a supersonic airstream at the outlet that produces coherentshock waves having a wavelength of 0.194 inches as a principal energycomponent. As used in this specification, the term coherent shock wavesmeans a series of pressure waves all having substantially the samedifference between successive peaks, i.e., the same wavelength. Thepressure waves are positive and unipolar, i.e., the pressure at a givenpoint varies between ambient pressure and a large positive pressure. Inother words, the pressure of coherent shock waves varies essentially inthe same manner as a rectified, base-clipped electrical sine wavesignal. In addition to the principal wavelength, the cells also produceother pressure wave components discussed in U.S. Pat. No. 3,554,443,which have secondary wavelengths that are multiples and/or submultiplesof the principal wavelength e.g., 0.194 inches. Cells 21 and 22 have aparticularly large energy component at the submultiple wavelength of0.097 inches because of the diameter of the openings at the upstreamends of their cell covers. In summary, cells 15, 17, 21, and 22 allproduce coherent shock waves having principal and secondary wavelengthsthat are multiply related.

Cavity 27 is cylindrical. The inside surface of spacer 16 defines thecylindrical side wall of cavity 27, the upstream end of the cover ofcell 17 defines the reflective end wall of cavity 27, and axis 18 is thelongitudinal axis of cavity 27. FIG. 5 is an isolated view of spacer 16in which the dimensions of cavity 27 are labelled. The distance alongaxis 18 from the upstream end of cavity 27 to intersection point 29 isX,, the distance along axis 18 from intersection point 29 to thedownstream end of cavity 27 is X the distance along axis 28 from theside wall of cavity 27 at the point where hole 24 is formed tointersection point 29 is Y,, and the'distance along axis 28 from theside wall of cavity 27 at the point where hole 26 is formed tointersection point 29 is Y In the disclosed embodiment, cavity 27 iscylindrical and holes 24 and 26 are spaced midway between the ends ofcavity 27. Thus, distances Y and Y, are the same, their sum equallingthe diameter of the cylinder, and distances X, and X, are the same,their sum equalling the length of the cylinder. The structure involvinghousing 10, cell 15, spacer 16, and cell 17, without cells 21 and 22,was disclosed in application Ser. No. 13,977, but is claimed herein.

The shock waves produced by cell 15 have a vertex that propagates alongaxis 18. The distances X, and X, are each equal to one half of theprincipal wavelength; thus the length of cavity 27 is 0.194 inches. As aresult, some of the shock waves produced by cell 15 are reflected fromthe upstream end of the cover of cell 17 and resonate in cavity 27 toenhance the intensity. It is believed the shock waves are converted tocoherent sonic wave energy by the resonant action.

In this specification, the term coherent sonic wave energy" meanspressure waves in which the energy is concentrated in terms of itsfrequency spectrum into a principal component with or without a numberof other components, and the pressure waves are bipolar, i.e., thepressure varies both positively and negatively from the ambient pressureso that concentration and rarifiare a plurality of components, the'multicomponent sonic wave energy is coherent in that the wavelengths ofall the components are multiples or submultip'les of the principalcomponent wavelength. Since the wavelengths of the components comprisingthe coherent sonic wave energy are all essentially multiply related,these components reinforce each other to form standing waves in anenclosed area and to-produce extremely large pressure gradients. Thedescribed coherent sonic wave energy produces much higher pressuregradients and, therefore, atomizing power, than comparable shock wavesdue to the bipolar nature of the sonic pressure wave.

Holes 23 and 24 and holes 25 and 26 have a-diameter equal to one half ofthe principle wavelength, i.e., 0.097 inches, so the shock waves fromcells 21 and 22 are coupled to cavity 27 by holes 23 through 26 withoutany appreciable attenuation. Thus, cells 21 and 22 have a virtual orapparent outlet at the side wall of cavity '27. The shock waves producedby cells 21' and 22 have vertices that propagate along transverse axis28 and collide with the vertex of the shock waves produced by cell l5atintersection point 29. The distances Y, and Y, are each equal to theprincipal wavelength; thus the radius of cavity 27 is 0.194 inches. Therelationship of the distances X,, X,, X, X,,.Y,, and Y,, to the shockwave wavelength further'enha'nces the resonant action in cavity 27 andincreases the intensity of the pressure wave energy. In a sense, fluidicreflective surfaces are formed at point 29 by the colliding of the shockwaves travelling along axis 18 and along axis 28. Since the distancesfrom these fluidic reflective surfaces to the side wall and the ends ofcavity 27 are multiples or submultiples of the wavelength of the shockwaves, these fluidic reflective surfaces promote with the sidewall andends further resonant action in cavity 27.

The coherent sonic wave energy produced in cavity 27 is drawn into cell17 where it is reconverted to coherent shock waves having a principalcomponent wavelength of 0.194 inches. The intensity of these shock wavesis appreciably higher than the intensity of the shock waves produced bythe device disclosed in application Ser. No. 13,977. This fact isattributable to the resonant interaction that takes place between shockwaves from cells 21 and 22 and the shock waves from cell 15.

The small diameter of theopenings at the upstream end of the cell coversof cells 21 and 22 reduces the mass flow rate of air through cells 21and 22 vis-a-vis the mass flow rate of air through cell 15. Thisprevents the shock waves produced by cells 21 and 22 from swamping theshock waves produced by cell and from disrupting the propagation ofshock waves along axis 18 to cell 17.

Although the preferred dimensions of distances X,, and Y, relative tothe principal wavelength are as stated above, the described increase inthe intensity of the shock waves can be realized with other specificdimensions. The basic rule to follow is that distances X,, X,, Y,, andY, and the principal wavelength are all multiply related. It is believedthe fluidic, reflective surface formed at the colliding shock wavesenhances the resonant action due to the solid reflective surfaces at theupstream end of the cover of cell 17 and around the inside of spacer 16.Although the optimum enhancecation of the fluid molecules alternatelyoccurs If there ment occurs when the above described multiplerelationship exists between the principal wavelength and the distancefrom the outlets of cells 15 and 21 to intersection point 29, thepressure wave intensity is also enhanced to some extent when themultiple relationship does not exist. Thus, the structure disclosed inFIG. 12 of application Ser. No. 13,977 insofar as it relates totransversely arranged cells is also claimed herein.

In FIG. 2, a resonant cavity 40 is enclosed'within a housing 41, whichcomprises a cylindrical tube 42, a cylindrical outer jacket 43, andtubular fittings 44 and 45. Fittings 44 and 45 are fixed to tube 42 byswaging or other means. Jacket 43, which surrounds tube 42, has a forcefit therewith. Annular spacers 46, 47, 48, and 49 are disposed withintube 42 along its cylindrical axis 50in abutting relationship betweenthe ends of fittings 44 and 45, as shown in FIG. 2. Thus, spacers 46through 49 fit snugly inside housing 41 as a single cylindrical unitwithout being able to move. A strip 51 of material is attached to spacer49 so it extends diametrically across spacer 49 (see FIG. 3) flush withthe end thereof. The space enclosed by spacers 46, 47, and 48 betweenfitting 44 and-strip 51 comprises cavity 40.

- Chordal openings 52 and 53 (see FIG. 3), which are defined by theedges of strip 51 and the inside wall of spacer 49, comprise the exitfrom cavity 40. Auxiliary cubicle cavities 54, 55, 56, and 57 (see FIG.3) are formed at 90 intervals around spacer 48 at the end abuttingspacer 49. Thus, cavities 54, 55, 56, and 57 communicate with cavity 40and intersect the plane in which strip 51 lies. A cylindricalcounterbore 58 is formed in jacket 43. A cylindrical shock wavegenerating cell 59, which is identical to cells 21 and 22 in FIG. 1, ismaintained in counterbore 58 by a force fit. A circular hole 60 throughtube 42 and a circular hole 61 through spacer 47 couple cell 59 tocavity 40. Counterbore 58, cell 59, and holes 60 and 61 are all centeredabout a transverse axis 62 that is perpendicular to axis 50 andintersects axis 50 at a point 63 within cavity 40.

' A shock wave generator 70, which is preferably the arrangementdisclosed in FIG- 1, but could be the shock wave generator disclosed inone of the referenced applications, or even a conventionalconvergingdiverging supersonic nozzle, is coupled to cavity 40 by aconnecting hose 71. A clamp 72 secures hose 71 to fixture 44 and a clamp73 secures hose 71 to a fitting on shock wave generator 70. It isassumed for the purpose of discussion that generator produces shockwaves having a principal component wavelength of 0.194 inches. Thewavelength of the shock waves, the underformed diameter of hose 71, andthe inside diameter of the fittings are all multiply relatedspecifically, the diameter of the hose and the inside diameter of thefittings are both twice the wavelength of the shock waves, e.g., 0.388inches. Accordingly, connecting hose 71 can be quite long withoutappreciably attenuating the shock waves.

Cavity 40 is cylindrical. The inside walls of spacers .46 through 47define the cylindrical side wall of cavity 40, strip 51 defines thereflective end surface of cavity 40, and axis 50 is the longitudinalaxis of cavity 40. FIG. 6 is an isolated view of spacers 46, 47, and 48in which the dimensions of cavity 40 are labelled. The distance alongaxis 50 from the upstream end of cavity 40 to intersection point 63 isX,, the distance along axis 50 from intersection point 63 to thedownstream end of cavity 40 is X and the distance along axis 62 from theequals the radius of the cylinder and the sum of distances X and X isequal to the length of the cylinder.

The shock waves produced by generator 70 are coupled by connecting hose71 to cavity 40 where they propagate along axis 50. The distance X is 2%times the principal wavelength, and the distance X is 1% times theprincipal wavelength; thus, the length of cavity 40 is 0.776 inches.Strip 51 reflects the vertex of the shock waves impinging upon it,thereby giving rise to resonant action due to the multiple relationshipof distances X and X, to the wavelength of the shock waves. The portionof strip 51 closely surrounding axis 50 most effectively reflects theimpinging shock waves, because it intercepts the protruding portion ofthe wavefront,'i.e., the vertex of the shock wave. Theoretically, thereflecting surface could be a circular piece of material centered as atarget at the end of cavity 40. In practice a strip shaped reflectingsurface is used to provide an easy to fabricate means for supporting thereflective surface at the end of cavity 40. The width of strip 50 isequal to a multiple or a submultiple of the principal wavelength,preferably one wavelength, i.e. 0.194 inches.

Holes 60 and 61 have a diameter equal to one-half of the principalwavelength, i.e., 0.097 inches, so the shock waves from cell 59 arecoupled to cavity 40 by holes 60 and 61 without any appreciableattenuation. Thus, cell 59 has a virtual or apparent outlet at the sidewall of cavity 40. The shock waves produced by cell 59 havea vertex thatpropagates along transverse axis 62 and collides with the vertex of theshock waves propagating along axis 50 at intersection point 63. DistanceY; is equal to the principal wavelength; thus, the radius of cavity 40is 0.194 inches. The relationship of the distances X X X, X and Y to theshock wave wavelength further enhances the resonant action in cavity 40in the manner described above in connection with FIG. 1, and increasesthe efficiency of the conversion to coherent sonic wave energy. As inthe arrangement of FIG. 1, attention is given to the mass flow ratethrough cell 59 so the shock waves produced by cell 59 do not disruptthe propagation of shock waves along axis 50. If desired cell 59 couldbe balanced by an identical cell entering cavity 40 from a hole in itsside wall opposite hole 61 and aligned with axis 62.

Cavities 54, 55, 56, and 57 intercept some of the energy reflectedoutwardly by strip 51. The sides of cavities 54 through 57 equal theprincipal wavelength. As a result, the intercepted energy is subjectedto resonant action in cavities 54 through 57, which still furtherenhances the conversion to coherent sonic wave energy.

The coherent sonic wave energy produced in cavity 40 leaves throughchordal openings sections 52 and 53 and propagates along the interior ofspacer 49 and fitting 45 to the point where it is utilized. Although thepreferred dimensions of distances X X and Y relative to the principalwavelength are as stated above, the efficient conversion of shock wavesto sonic waves can be realized with other dimensions. The basic rule tofollow is that the principal dimensions i.e., distances X X and Y,, thewavelength, the sides of cavities 53 through 57, and the width of stripare all multiply related. As a result, the described types of resonantaction occur within cavity 40. Under some circumstances some .of thesedimensions are not significant. For example, in the embodiment disclosedin FIG. 2, fitting 44 and hose 71 have the same diameter as cavity 40.The entrance to cavity 40 merely appears as an extension'of hose 71 andfitting 44. Accordingly, distance X, of cavity 40 is not important.Distance X, only becomes significant when the shock wave generator isvery close to its cavity, i.e., a distance of several wavelengths. Anembodiment where X, is significant is described below in connection withFIG. 4.

The arrangement of FIG. 1 is a highly efficient shock wave generator;the arrangement of FIG. 2 is a highly efficient converter of coherentenergy from shock waves to sonic waves. In the arrangement of FIG. 4,the components of FIGS. 1 and 2 are combined in a common housing havingtubular fittings 71 and 72. The components of FIGS. 1 and 2.bear thesame reference numerals in FIG. 4. Cell 59 has been rotated 90 in FIG. 4so it is disposed midway between cells 21 and 22, the latter of which isnot visible in FIG. 4. The arrangement of FIG. 4 is a compact sonic wavegenerator capable of producing coherent sonic wave energy of highintensity.

The cells, housings, and spacers of FIGS. 1, 2, and 4 are functionallyintegral with each other. They are physically separate units only tofacilitate fabrication and assembly. Therefore, different physicaldivisions of the arrangements of FIGS. 1, 2, and 4 could be madedepending upon the particular mode of fabrication and assembly used.

In practice, resonance is not completely destroyed until the wavelengthof the shock waves deviates by one quarter wavelength from itsprescribed value relative to the dimensions of the cavities, i.e., fromthe multiple relationship. As a design guide, when the actualdimensional relationships between shock wave wavelength and cavities aremet to within 2 10 percent of the prescribed values, the describedresults are in fact achieved. Beyond a i 10 percent deviation, theresults drop off, but may still be usable.

FIG. schematically represents a conventional PCV system in' an internalcombustion engine and a pressure wave generator constructed according tothe invention functioning with the PCV system. The engine has an aircleaner 75, a carburetor 76 with a butterfly throttle valve 77, and anengine enclosed within a crankcase manifold 78. The combustiblecrankcase emissions produced in the course of the operation of theengine comprise blowby gases, i.e., incompletely combusted substancesthat escape from the combustion cylinders via the piston rings, and oilparticles that become suspended in the air within the crankcasemanifold. The PCV system returns these crankcase emissions to the intakesystem of the engine, at the base of the carburetor as shown or at theintake manifold, for recombustion in the engine. Clean air is coupledfrom cleaner by a connecting hose 80 to the crankcase manifold throughan oil filler cap 81. This clean air, represented by arrows 82, mixeswith and carries the blowby gases, represented by arrows 83, out ofcrankcase manifold 78 through a PCV valve 84 as represented by arrows85. PCV valve 84 is coupled to the intake system by a connecting hose86, which serves as the PCV or oil gallery return line. The describedPCV system is conventional. The only modification that is desirable isto provide a spring having a smaller spring constant for PCV valve 84.This enables PCV valve 84 to operate normally, i.e., to close duringidling and deceleration, de-' V spite. the smaller pressure drops thathave been found to exist in'the presence of a pressure wave generator.To install a pressure wave generator 87, which is one of the devicesdisclosed in FIGS. 1 through 4, hose 86 is simply cut and the two endsformed by the cut are joined to the respective fittings of pressure wavegenerator 87.

As the mixture of combustible crankcase emissions and air passes throughpressure wave generator 87, this mixture is energized, thereby becomingdirectly atomized. In addition, the pressure waves propagate into theintake system, as represented by the dots between pressure wavegenerator 87 and carburetor 76, and atomize indirectly the combustiblemixture entering the intake manifold from the carburetor. This indirectatomization is particularly effective when pressure wave generator 87 isa sonic wave generator that produces coherent sonic wave energy. In suchcase, the coherent sonic waves propagate into the intake system in anorderly fashion to form a standing wave veil across the outlet ofcarburetor 76 through which the combustible mixture formed in thecarburetor must pass before entering the intake manifold. The result isthat the combustible mixture from the carburetor is finely atomized.Although a shock wave generator is also an effective pressure wavegenerator, it is not as efficient as acoherent sonic wave generator. Theshock waves are reflected haphazardly from the first obstruction intheir path and then dissipate. Thus, their range is substantially lessthan the range of coherent sonic waves. The arrangement of FIG. 7 isclaimed in application Ser. No. 158,915, filed July 1, 1971.

The term fluid as used herein refers to gas and also refers to liquid tothe extent applicable.

The described embodiments of the invention are only considered to bepreferred and illustrative of the inventive concept; the scope of theinvention is not to be restricted to such embodiments. Various andnumerous other arrangements may be devised by one skilled in the artwithout departing from the spirit and scope of this invention as definedin the claims. For example, the disclosed pressure wave generators canbe used in applications other than the PCV return line of an internalcombustion engine; and the axes of the transversely arranged shock wavegenerating cells can be other than perpendicular; and cavities 54through 57 can have unequal sides, i.e., they can be hexahedral.

Reference is made to my application Ser. No. 217,124, filed Jan. 12,1972, which claims part of the subject matter disclosed herein.

What is claimed is:

l. A pressure wave generator comprising:

a first boundary layer formed shock wave generating cell having anoutlet disposed about a longitudinal axis, the first cell producing atits outlet shock waves having a predetermined wavelength and a vertexthat propagates along the longitudinal axis;

a second boundary layer formed shock wave generating cell having anoutlet disposed about an axis transverse to and intersecting thelongitudinal axis, the second cell producing at its outlet shock waveshaving a predetermined wavelength and a vertex that propagates along thetransverse axis;

an enclosure forming a passage along the longitudinal axis, the outletsof the first and second cells being coupled to the passage so the shockwaves produced by the first and second cells collide in the longitudinalpassage at the point of intersection of the axes; the distance along thelongitudinal axis between the outlet of the first cell and thepoint ofintersection of the axes, along the transverse axis between the outletof the second cell and the point of intersection of the axes, and thepredetermined wavelengths of the shock wqves produced by the first andsecond cells all being multiples of a common divisor; and a reflectivestrip of material extending diametrically acrossthe passage in the pathof the shock waves produced by the first cell, exits being formed by thespaces between the strip and the passage. 2. The pressure wave generatorof claim 1, in which at least one hexahedral resonant cavity is formedin the enclosure in communication with the passage intersect- I ing theplane defined by the reflective strip, the sides of the cavity beingmultiples of the common divisor.

3. The pressure wave generator of claim 1, in which four cubicleresonant cavities are formed at 90 intervals around the enclsoure incommunication with the longitudinal passage substantially in the planedefined by the reflective strip, the sides of the cavities being amultiple of the common divisor.

4. The pressure wave generator of claim 1, in which the longitudinalpassage is cylindrical, the exit is a pair of semi-circular openings oneither side of the strip, and the length and radius of the cylindricalpassage are multiples of the common divisor.

5. The pressure wave generator of claim 4, in which the intensity of theshock waves produced by the first cell is higher than the shock wavesproduced by the second cell.

6. The pressure wave generator of claim 5, in which the predeterminedwavelength of the shock waves produced by the first cell is a largermultiple than the predetermined wavelength of the shock waves producedby the second cell.

7. The pressure wave generator of claim 1, in which the enclosurecomprises a'housing that surrounds the first cell and a spacer in thehousing between the first cell and the reflective strip, the passagecomprises a hole through the spacer, the second cell is fixed to theside of the housing, and the housing and the spacer have through themaligned radial holes that form the outlet of the second cell.

8. The pressure wave generator of claim 7, in which the mass flow ratethrough the second cell is more limited than the mass flow rate throughthe first cell.

9. A pressure wave generator comprising: a resonant cavity having a pairof spaced ends, a cylindrical side wall interconnecting the ends, and alongitudinal axis extending between the ends;

first means for introducing into the cavity atone of the ends shockwaves having a vertex that propagates along the longitudinal axis andhaving a pre determined wavelength;

second means for introducing into the cavity at the side wall shockwaves having a vertex that propagates along an axis transverse to andintersecting the longitudinal axis and having a predeterminedwavelength, the distance between the point of introduction at the sidewall and the longitudinal axis, the distance between the transverse axisand the other end of the cavity, and the predetermined wavelengths beingmultiples of the common divisor;

a reflective strip diametrically disposed at the other end of thecavity; and

an exit from the cavity at the other end for shock waves that collide atthe point of intersection of the axes, the exit being formed between thestrip and the adjacent portions of the side wall.

10. The pressure wave generator of claim 9, in which the distancebetween the ends is a multiple of the common divisor.

11. The pressure wave generator of claim 9, in which the shock wavesintroduced at the one end have a higher momentum than the shock wavesintroduced at the side wall.

12. The pressure wave generator of claim 9, in which the width of thestrip is a multiple of the common divisor.

13. The pressure wave generator of claim 9, in which a plurality ofhexahedral auxiliary cavities are formed in the side wall at the otherend, the sides of the auxiliary cavities being multiples of the commondivisor.

14. The pressure wave generator of claim 13, in which the resonantcavity comprises a plurality of adjacent annular spacers and a housingsurrounding the spacers, the spacers defining the side wall of thecavity; the second means for introducing shock waves into the cavitycomprises a boundary layer formed shock wave generating cell fixed tothe side of the housing, the.

housing and the spacer adjacent to the cell having through them alignedradial holes to couple the cell to the cavity, the reflective strip isfixed to one of the spacers at one end, and .the auxiliary cavities areformed in another spacer at one end adjacent to the strip to interceptenergy reflected from the strip.

15. A pressure wave generator comprising:

an enclosure having spaced ends and a longitudinal cylindrical side wallextending between the ends about an axis; means for introducing into theenclosure at one end pressure waves having a vertex that propagatesalong the longitudinal axis and having a predetermined wavelength, thepredetermined wavelength and the distance between the ends beingmultiples of a common divisor to promote resonant action in theenclosure; a reflective strip diametrically disposed at the other end;and

arcuate exits from the enclosure formed at the other end by 'the stripand the adjacent portions of the side wall to permit pressure waveenergy to leave the enclosure at the other end.

16. The pressure wave generator of claim 15, in which the width of thestrip is a multiple of the common divisor.

17. The pressure wave generator of claim 16, in which a plurality ofhexahedral cavities are formed at the other end in communication withthe energy reflected from the strip, the sides of the cavities beingmultiples of the common divisor.

1. A pressure wave generator comprising: a first boundary layer formedshock wave generating cell having an outlet disposed about alongitudinal axis, the first cell producing at its outlet shock waveshaving a predetermined wavelength and a vertex that propagates along thelongitudinal axis; a second boundary layer formed shock wave generatingcell having an outlet disposed about an axis transverse to andintersecting the longitudinal axis, the second cell producing at itsoutlet shock waves having a predetermined wavelength and a vertex thatpropagates along the transverse axis; an enclosure forming a passagealong the longitudinal axis, the outlets of the first and second cellsbeing coupled to the passage so the shock waves produced by the firstand second cells collide in the longitudinal passage at the point ofintersection of the axes; the distance along the longitudinal axisbetween the outlet of the first cell and the point of intersection ofthe axes, along the transverse axis between the outlet of the secondcell and the point of intersection of the axes, and the predeterminedwavelengths of the shock wqves produced by the first and second cellsall being multiples of a common divisor; and a reflective strip ofmaterial extending diametrically across the passage in the path of theshock waves produced by the first cell, exits being formed by the spacesbetween the strip and the passage.
 2. The pressure wave generator ofclaim 1, in which at least one hexahedral resonant cavity is formed inthe enclosure in communication with the passage intersecting the planedefined by the reflective strip, the sides of the cavity being multiplesof the common divisor.
 3. The pressure wave generator of claim 1, inwhich four cubicle resonant cavities are formed at 90* intervals aroundthe enclsoure in communication with the longitudinal passagesubstantially in the plane defined by the reflective strip, the sides ofthe cavities being a multiple of the common divisor.
 4. The pressurewave generator of claim 1, in which the longitudinal passage iscylindrical, the exit is a pair of semi-circular openings on either sideof the strip, and the length and radius of the cylindrical passage aremultiples of the common divisor.
 5. The pressure wave generator of claim4, in which the intensity of the shock waves produced by the first cellis higher than the shock waves produced by the second cell.
 6. Thepressure wave generator of claim 5, in which the predeterminedwavelength of the shock waves produced by the first cell is a largermultiple than the predetermined wavelength of the shock waves producedby the second cell.
 7. The pressure wave generator of claim 1, in whichthe enclosure comprises a housing that surrounds the first cell and aspacer in the housing between the first cell and the reflective strip,the passage comprises a hole through the spacer, the second cell isfixed to the side of the hoUsing, and the housing and the spacer havethrough them aligned radial holes that form the outlet of the secondcell.
 8. The pressure wave generator of claim 7, in which the mass flowrate through the second cell is more limited than the mass flow ratethrough the first cell.
 9. A pressure wave generator comprising: aresonant cavity having a pair of spaced ends, a cylindrical side wallinterconnecting the ends, and a longitudinal axis extending between theends; first means for introducing into the cavity at one of the endsshock waves having a vertex that propagates along the longitudinal axisand having a predetermined wavelength; second means for introducing intothe cavity at the side wall shock waves having a vertex that propagatesalong an axis transverse to and intersecting the longitudinal axis andhaving a predetermined wavelength, the distance between the point ofintroduction at the side wall and the longitudinal axis, the distancebetween the transverse axis and the other end of the cavity, and thepredetermined wavelengths being multiples of the common divisor; areflective strip diametrically disposed at the other end of the cavity;and an exit from the cavity at the other end for shock waves thatcollide at the point of intersection of the axes, the exit being formedbetween the strip and the adjacent portions of the side wall.
 10. Thepressure wave generator of claim 9, in which the distance between theends is a multiple of the common divisor.
 11. The pressure wavegenerator of claim 9, in which the shock waves introduced at the one endhave a higher momentum than the shock waves introduced at the side wall.12. The pressure wave generator of claim 9, in which the width of thestrip is a multiple of the common divisor.
 13. The pressure wavegenerator of claim 9, in which a plurality of hexahedral auxiliarycavities are formed in the side wall at the other end, the sides of theauxiliary cavities being multiples of the common divisor.
 14. Thepressure wave generator of claim 13, in which the resonant cavitycomprises a plurality of adjacent annular spacers and a housingsurrounding the spacers, the spacers defining the side wall of thecavity; the second means for introducing shock waves into the cavitycomprises a boundary layer formed shock wave generating cell fixed tothe side of the housing, the housing and the spacer adjacent to the cellhaving through them aligned radial holes to couple the cell to thecavity, the reflective strip is fixed to one of the spacers at one end,and the auxiliary cavities are formed in another spacer at one endadjacent to the strip to intercept energy reflected from the strip. 15.A pressure wave generator comprising: an enclosure having spaced endsand a longitudinal cylindrical side wall extending between the endsabout an axis; means for introducing into the enclosure at one endpressure waves having a vertex that propagates along the longitudinalaxis and having a predetermined wavelength, the predetermined wavelengthand the distance between the ends being multiples of a common divisor topromote resonant action in the enclosure; a reflective stripdiametrically disposed at the other end; and arcuate exits from theenclosure formed at the other end by the strip and the adjacent portionsof the side wall to permit pressure wave energy to leave the enclosureat the other end.
 16. The pressure wave generator of claim 15, in whichthe width of the strip is a multiple of the common divisor.
 17. Thepressure wave generator of claim 16, in which a plurality of hexahedralcavities are formed at the other end in communication with the energyreflected from the strip, the sides of the cavities being multiples ofthe common divisor.